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      1 // Copyright 2016 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/sequence_token.h"
      6 
      7 #include "base/atomic_sequence_num.h"
      8 #include "base/lazy_instance.h"
      9 #include "base/logging.h"
     10 #include "base/threading/thread_local.h"
     11 
     12 namespace base {
     13 
     14 namespace {
     15 
     16 base::StaticAtomicSequenceNumber g_sequence_token_generator;
     17 
     18 base::StaticAtomicSequenceNumber g_task_token_generator;
     19 
     20 LazyInstance<ThreadLocalPointer<const SequenceToken>>::Leaky
     21     tls_current_sequence_token = LAZY_INSTANCE_INITIALIZER;
     22 
     23 LazyInstance<ThreadLocalPointer<const TaskToken>>::Leaky
     24     tls_current_task_token = LAZY_INSTANCE_INITIALIZER;
     25 
     26 }  // namespace
     27 
     28 bool SequenceToken::operator==(const SequenceToken& other) const {
     29   return token_ == other.token_ && IsValid();
     30 }
     31 
     32 bool SequenceToken::operator!=(const SequenceToken& other) const {
     33   return !(*this == other);
     34 }
     35 
     36 bool SequenceToken::IsValid() const {
     37   return token_ != kInvalidSequenceToken;
     38 }
     39 
     40 int SequenceToken::ToInternalValue() const {
     41   return token_;
     42 }
     43 
     44 SequenceToken SequenceToken::Create() {
     45   return SequenceToken(g_sequence_token_generator.GetNext());
     46 }
     47 
     48 SequenceToken SequenceToken::GetForCurrentThread() {
     49   const SequenceToken* current_sequence_token =
     50       tls_current_sequence_token.Get().Get();
     51   return current_sequence_token ? *current_sequence_token : SequenceToken();
     52 }
     53 
     54 bool TaskToken::operator==(const TaskToken& other) const {
     55   return token_ == other.token_ && IsValid();
     56 }
     57 
     58 bool TaskToken::operator!=(const TaskToken& other) const {
     59   return !(*this == other);
     60 }
     61 
     62 bool TaskToken::IsValid() const {
     63   return token_ != kInvalidTaskToken;
     64 }
     65 
     66 TaskToken TaskToken::Create() {
     67   return TaskToken(g_task_token_generator.GetNext());
     68 }
     69 
     70 TaskToken TaskToken::GetForCurrentThread() {
     71   const TaskToken* current_task_token = tls_current_task_token.Get().Get();
     72   return current_task_token ? *current_task_token : TaskToken();
     73 }
     74 
     75 ScopedSetSequenceTokenForCurrentThread::ScopedSetSequenceTokenForCurrentThread(
     76     const SequenceToken& sequence_token)
     77     : sequence_token_(sequence_token), task_token_(TaskToken::Create()) {
     78   DCHECK(!tls_current_sequence_token.Get().Get());
     79   DCHECK(!tls_current_task_token.Get().Get());
     80   tls_current_sequence_token.Get().Set(&sequence_token_);
     81   tls_current_task_token.Get().Set(&task_token_);
     82 }
     83 
     84 ScopedSetSequenceTokenForCurrentThread::
     85     ~ScopedSetSequenceTokenForCurrentThread() {
     86   DCHECK_EQ(tls_current_sequence_token.Get().Get(), &sequence_token_);
     87   DCHECK_EQ(tls_current_task_token.Get().Get(), &task_token_);
     88   tls_current_sequence_token.Get().Set(nullptr);
     89   tls_current_task_token.Get().Set(nullptr);
     90 }
     91 
     92 }  // namespace base
     93